Analysis of LED Lighting Application in Cold Region
After 10 years of rapid development, LED lighting has entered a rapid promotion stage, and the market application has gradually expanded from the initial southern region to the central and western regions. However, in actual application, we found that the outdoor lighting products used in the south are well tested in the northern regions, especially the northeast. This article analyzes some of the key factors that affect LED lighting in cold environments, finds out corresponding solutions, and finally brings out the advantages of LED light sources.
First, the advantages of LED lighting in cold environments
Compared with the original incandescent lamp, fluorescent lamp and high-intensity gas discharge lamp, the operating performance of the LED device is much better at low temperature, and it can even be said that the optical performance is more excellent than at ordinary temperature. This is closely related to the temperature characteristics of the LED device. As the junction temperature decreases, the luminous flux of the lamp will increase relatively. According to the heat dissipation law of the lamp, the junction temperature is closely related to the ambient temperature. The lower the ambient temperature, the lower the junction temperature is bound to be. In addition, lowering the junction temperature can also reduce the light decay process of the LED light source and delay the service life of the lamp, which is also a characteristic of most electronic components.
Difficulties and Countermeasures of LED Lighting in Cold Environment
Although LED itself has more advantages in cold conditions, it cannot be ignored that in addition to light sources. LED lamps are also closely related to driving power, lamp body materials, and foggy weather, strong ultraviolet and other comprehensive weather in cold environments. Factors have brought new challenges and troubles to the application of this new light source. Only by clarifying these constraints and finding corresponding solutions, can we give full play to the advantages of LED light sources and shine in the cold environment.
1. Low temperature startup problem of driving power supply
Everyone who does power supply development knows that low temperature starting of the power supply is a problem. The main reason is that most of the existing mature power solutions are inseparable from the extensive application of electrolytic capacitors. However, in a low temperature environment below -25 ° C, the electrolytic activity of the electrolytic capacitor is significantly reduced, and the capacitance capacity is greatly attenuated, which causes the circuit to malfunction. To solve this problem, there are currently two solutions: one is to use high-quality capacitors with a wider operating temperature range, which of course will increase costs. The second is the circuit design using electrolytic capacitors, including ceramic laminated capacitors, and even other driving schemes such as linear drive.
In addition, under the low temperature environment, the withstand voltage performance of ordinary electronic devices will also decrease, which will adversely affect the overall reliability of the circuit, which requires special attention.
2. Reliability of plastic materials under high and low temperature impact
According to experiments conducted by researchers at some research institutes at home and abroad, many ordinary plastic and rubber materials have poor toughness and increased brittleness at low temperatures below -15 ° C. For LED outdoor products, transparent materials, optical lenses, seals and some structural parts may use plastic materials, so the low-temperature mechanical properties of these materials need to be carefully considered, especially the load-bearing components, to avoid lamps in Under the low temperature environment, it will rupture after being hit by strong wind and accidental collision.
In addition, LED luminaires often use a combination of plastic parts and metal. Because the expansion coefficients of plastic materials and metal materials are very different under large temperature differences, for example, the expansion coefficients of metal aluminum and plastic materials commonly used in lamps are about 5 times different, which may cause plastic materials to crack or the gap between the two. If it is increased, the waterproof seal structure will eventually be invalidated, which will cause product problems.
In the alpine region, from October to April of the following year, it may be in the snow and ice season. The temperature of the LED lamp may be lower than -20 ℃ near the evening before the lamp is turned on in the evening, and then after the electricity is turned on at night, the temperature of the lamp body may rise to 30 ℃ ～ 40 ℃ due to the heating of the lamp. Experience a high and low temperature cycle shock. In this environment, if the structural design of the luminaire and the problem of matching different materials are not handled well, it is easy to cause the problems of material cracking and waterproof failure mentioned above.